Integrated multi-function return tube for combo heat exchangers

ABSTRACT

A heat exchanger having an improved oil cooler section is provided. The oil cooler section includes a first manifold, a second manifold, an oil inlet port, an oil outlet port, cooling tubes, and a return tube. The first and second manifold are located in spaced relationship and the oil inlet and outlet port are located proximate each other toward one side of the heat exchanger. The cooling tubes are connected between the first and second manifold, each tube defining an oil flow passage. The return tube also be connected between the first and second manifold and defining an oil return passage. The oil return passage has a cross-sectional area larger than each of the oil flow passages allowing the oil to be returned along a low pressure flow path.

BACKGROUND

1. Field of the Invention

The present invention generally relates to a heat exchanger that includes an oil cooler section.

2. Description of Related Art

Generally, an automotive vehicle includes one or more heat exchangers for cooling fluids used in the vehicle systems, such as, refrigerant for an air conditioning system or transmission oil for a transmission device. A common heat exchanger comprises a plurality of parallel tubes connected at each end to a manifold and spaced apart by corrugated fins. Typically the tubes are formed of extruded aluminum. The manifolds include an inlet for receiving the fluid to be cooled and an outlet for supplying cooled fluid to other components in the system. The fluid enters the manifold through the inlet and is distributed to flow through passages within the tubes. Heat is extracted by air that flows through spaces between the corrugated fins located between the tubes. The manifolds may include baffles that divide the manifold into sections and route the fluid back and forth in multiple passes.

It is known to manufacture a heat exchanger that is divided into separate sections for cooling different fluids. For example, heat exchangers are available that include a condenser section for cooling refrigerant and an oil cooler section for cooling transmission oil. The manifolds are divided by baffles to segregate the fluids. The tubes include multiple internal webs to strengthen the outer walls and prevent distortion. The webs divide the cross section of the tubes into discrete regions of relatively small area. Because the refrigerant enters the heat exchanger as a gas, such small regions are effective in cooling and condensing the refrigerant.

On the other hand, the transmission oil flowing through the oil cooler section is a liquid having a relatively low pressure and a relatively high viscosity. The oil tubes also include internal webs to increase surface area in contact with the transmission oil. However, the internal webs resist the flow of oil further increasing the required pressure to generate oil flow through the tubes. Due to these constraints, oil inlet and outlet ports are typically located on opposite sides of the heat exchanger.

In many packaging situations it is desirable to have the inlet and outlet port on the same side of the heat exchanger. Because of the relatively high pressure of the refrigerant within the condenser section, a U-flow configuration may be used. In this configuration, the refrigerant flows from a first manifold through a first set of the tubes to a second manifold. To return the refrigerant back to the first manifold, the refrigerant flows through a second set of tubes forming a “U” shaped flow path. In the oil cooler section, the pressure loss through the tubes and manifolds makes a U-flow configuration impractical to return the transmission oil to the first manifold.

In view of the above, it is apparent that there exists a need for a heat exchanger including an improved oil cooler section.

SUMMARY

In satisfying the above need, as well as overcoming the enumerated drawbacks and other limitations of the related art, the present invention provides a heat exchanger having an improved oil cooler section.

The oil cooler section includes a first manifold, a second manifold, an oil inlet port, an oil outlet port, cooling tubes, and a return tube. The first and second manifold are located in spaced relationship and the oil inlet and outlet port are located proximate each other toward one side of the heat exchanger. The cooling tubes are connected between the first and second manifold, each tube defining an oil flow passage. The return tube also being connected between the first and second manifold and defining an oil return passage. The oil return passage has a cross-sectional area equal or larger than the summation of each of the oil flow passages allowing the oil to be returned along a low pressure flow path.

In another aspect of the present invention, heat exchanger includes fins disposed between and attached to the cooling tubes to form a fin-tube assembly. Further, the return tube has a flat portion, forming a D-shaped cross section, to facilitate brazing of the return tube to the fin-tube assembly. In addition, the return tube has a circular section at either or both ends of the return tube to facilitate connection of the return tube to the first and second manifold.

In another aspect of the present invention, the return tube includes an inlet port and outlet port located on the return tube. In addition, a mounting flange is provided integrally with the return tube for attachment of external componentry.

In yet another aspect of the present invention, the return tube is configured to provide structural support the heat exchanger. The return tube is comprised of aluminum with a wall thickness between 1.0 and 1.5 mm

Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view, partially cutaway, showing a combination heat exchanger in accordance with the present invention;

FIG. 2 is an isometric view of a heat exchanger with oil inlet and outlet ports located on the oil return tube;

FIG. 3 is an isometric view illustrating a method of assembling a heat exchanger in accordance with the present invention; and

FIG. 4 is an isometric sectional view of the oil return tube.

DETAILED DESCRIPTION

Referring now to FIG. 1, a heat exchanger embodying the principles of the present invention is illustrated therein and designated at 10. The heat exchanger 10 is adapted for use in an automotive vehicle and includes a first section 12 and a second section 14 for cooling different fluids. In a preferred embodiment, section 12 is a condenser for cooling refrigerant for an air conditioning system. Also in a preferred embodiment, section 14 is adapted for cooling transmission oil, and is referred to herein as a transmission oil cooler section. Alternately, heat exchanger 10 may be adapted for cooling other fluids.

Heat exchanger 10 comprises a first manifold 16 and a second manifold 18 in spaced, parallel relationship. Baffles 19 and 20 divide each manifold 16 and 18 into first chambers 22 and 24 for condenser section 12 and second chambers 26 and 28 for oil cooling section 14. In addition, the manifolds may include baffles, for example, baffle 21 that further divide the chambers into portions for routing the fluids through the section along a particular flow path. Referring to condenser section 12, the section further includes a plurality of tubes 30 that extend between manifolds 16 and 18 and define flow passages in fluid communication with chambers 22 and 24. Condenser section 12 further comprises an inlet 32 and an outlet 34. During operation in an automotive air conditioning system, inlet 32 is coupled to a compressor for receiving warm refrigerant therefrom, and outlet 34 is coupled to an evaporator for discharging cooled refrigerant thereto. Within the condenser section 12, the refrigerant is distributed through chambers 26 and 28 to flow through the flow paths within tubes 30, whereupon the refrigerant is cooled as a result of heat extracted by air flowing within the spaces between the tubes. Fins 36 disposed within the spaces between the tubes further enhances heat transfer from the fluid to the air.

Referring now to oil coolant section 14, the section includes a plurality of tubes 40 that extend between manifolds 16 and 18 and include flow passages in fluid communication with chambers 26 and 28. The tubes are in spaced, parallel arrangement. Fins 36 are disposed between the tubes to enhance heat transfer with cooling air caused to flow through the space between the tubes. A connection block 42 includes an inlet 44 and an outlet 46. During operation, inlet 44 is coupled to a transmission case for receiving warm transmission oil therefrom, and directs the oil into chamber 26. The oil flows from chamber 26 through the oil passages within tubes 40, whereupon the oil is cooled by air flowing through the spaces between the tubes. The oil flows from the tubes into chamber 28 and is returned through an oil return tube 48 to connection block 42 for discharge through outlet 46, which is coupled to return the cooled oil to the transmission case. Return tube 48 has an oil return passage with a cross sectional area equal or larger than the summation of the cross sectional area of the oil flow passages in tubes 40. In addition, the return tube 48 is configured with a wall thickness to provide additional strength to heat exchanger 10. For example, the return tube 48 may be comprised of aluminum with a wall thickness of between 1.0 and 1.5 mm. In addition, the aluminum may be a 3000 or 6000 series aluminum and provided in a clad or no-clad configuration.

Now referring to FIG. 2, another embodiment of the heat exchanger is provided. In the configuration shown, the return tube 48 includes an inlet port 50 and outlet port 52 located on the return tube 48. In certain packaging situations, it may be desirable to provide access to the inlet and outlet ports from the return tube side of heat exchanger. In addition, a mounting flange 54 may be provided integral with the return tube for external or adjacent componentry.

Now referring to FIG. 3, a method of assembling a heat exchanger is illustrated. The fins 36 are disposed between and attached to the tubes 40 to form a fin-tube assembly 60. The return tube 48 is positioned along and attached to the fin-tube assembly 60 providing additional support to the fin-tube assembly 60. The return tube 48 is preferably brazed to the fin-tube assembly 60 and the cross section of the return tube 48 is configured to facilitate this process as described below.

Now referring to FIG. 4, a cross sectional view of the return tube 48 is provided. A return tube 48 has a flat portion 70 to provide an improved surface to attach the return tube 48 to the fin-tube assembly 60. The flat portion 70 cooperates with the round portion of the return tube 48 to form a generally “D” shaped cross section 72. The “D” shaped cross section 72 provides for optimal oil flow while also providing a flat surface to facilitate brazing of the return tube 48 to the fin-tube assembly 60. To facilitate assembly of the heat exchanger, the end of the return tube 48 has a round section 74. The return tube 48 transitions from the “D” shaped section 72 where it is attached to the fin-tube assembly 60 to the round section 74 where it connects to the first manifold 16. Preferably, the return tube 48 is round at both ends facilitating ease of connection to both the first and second manifold 16, 18.

Referring again to FIG. 3, cooling tube openings 64 are provided in the first manifold 16 to facilitate the flow of oil between the first manifold 16 and the tubes 40. Further, a return tube opening 66 matching the size of the return tube 48 is provided to facilitate the return of the oil to the first manifold 16. The first manifold 16 is positioned with the openings 64, 66 being received over the tubes 40 and return tube 48. With the first manifold 16 in this configuration, the assembly is washed, fluxed, and brazed. In a similar manner, the second manifold 18 is positioned over the tubes 40 and return tube 48 and attached to the assembly. Preferably, the system is configured to position the first and second manifold 16, 18 at the same time, allowing the brazing of first and second manifold 16, 18 in a single step. Use of the return tube 48 eliminates the need for a brazed iron, as the return tube 48 provides enough structure during the brazing process to ensure robust fin and tube brazing joints.

As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims. 

1. A heat exchanger having an oil cooler section, the oil cooler section comprising: a first manifold and a second manifold in spaced relationship; an oil inlet port and an oil outlet port, wherein the oil inlet port is located proximate the oil outlet port; a plurality of tubes, each tube defining an oil flow passage and having a first end connected to the first manifold with the oil flow passage in fluid communication therewith, and a second end connected to the second manifold with the oil flow passage in fluid communication therewith; and a return tube defining an oil return passage, the return tube having a first end connected to the first manifold with the oil return passage in fluid communication therewith, and a second end connected to the second manifold with the oil return passage in fluid communication therewith, the oil return passage having a cross sectional area equal or larger than the summation of the cross sectional area of all the oil flow passages.
 2. The heat exchanger of claim 1, further comprising fins disposed between the plurality of tubes to enhance heat transfer.
 3. The heat exchanger of claim 2, wherein the fins are attached to the plurality of tubes to form a fin-tube assembly.
 4. The heat exchanger of claim 3, wherein the return tube is attached to the fin-tube assembly.
 5. The heat exchanger of claim 4, wherein the return tube has a flat portion and the flat portion of the return tube is attached to the fin-tube assembly.
 6. The heat exchanger of claim 5, wherein the return tube has a generally D-shaped cross section.
 7. The heat exchanger of claim 1, wherein the return tube includes a mounting flange.
 8. The heat exchanger of claim 1, wherein the oil inlet port is located on the return tube.
 9. The heat exchanger of claim 1, wherein the oil outlet port is located on the return tube.
 10. The heat exchanger of claim 1, wherein the return tube is comprised of Aluminum.
 11. The heat exchanger of claim 1, wherein the wall thickness of the return tube is configured to provide mechanical support to the heat exchanger.
 12. The heat exchanger of claim 11, wherein the wall thickness of the return tube is between 1.0 and 1.5 mm.
 13. The heat exchanger of claim 1, wherein the return tube has a circular portion at the first end of the return tube.
 14. A method of assembling a heat exchanger, the method comprising: attaching fins between a plurality of tubes to form a fin-tube assembly; attaching a return tube to the fin-tube assembly; creating openings in a first manifold; positioning the openings in the first manifold over the plurality of tubes and the return tube. attaching the first manifold to the plurality of tubes and the return manifold.
 15. The method of claim 14, wherein attaching the first manifold to the plurality of tubes and the return tube includes brazing the first manifold to the plurality of tubes and the return tube.
 16. The method of claim 14, further comprising: creating openings in a second manifold; positioning the openings in the second manifold over the plurality of tubes and the return tube. attaching the second manifold to the plurality of tubes and the return manifold.
 17. The method of claim 16, wherein attaching the second manifold to the plurality of tubes and the return tube includes brazing the first manifold to the plurality of tubes and the return tube.
 18. The method of claim 16, wherein the steps of attaching the first manifold and attaching the second manifold are performed at the same time. 